Add SERD_READ_EXACT_BLANKS flag

This allows suppressing the blank node ID clashing mechanism to read blank IDs
exactly as they appear in the input, even if they match the scheme used to
generate blank node IDs internally.

2 files changed, 4 insertions, 3 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index a98b2b8a..b0892573 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -1566,8 +1566,9 @@ typedef struct SerdReaderImpl SerdReader;
 
 /// Reader options
 typedef enum {
-  SERD_READ_LAX       = 1u << 0u, ///< Tolerate invalid input where possible
-  SERD_READ_VARIABLES = 1u << 1u  ///< Support variable nodes
+  SERD_READ_LAX          = 1u << 0u, ///< Tolerate invalid input where possible
+  SERD_READ_VARIABLES    = 1u << 1u, ///< Support variable nodes
+  SERD_READ_EXACT_BLANKS = 1u << 2u, ///< Allow clashes with generated blanks
 } SerdReaderFlag;
 
 /// Bitwise OR of SerdReaderFlag values
diff --git a/src/n3.c b/src/n3.c
index 517dce8f..14f5aec1 100644
--- a/src/n3.c
+++ b/src/n3.c
@@ -1090,7 +1090,7 @@ read_BLANK_NODE_LABEL(SerdReader* const reader,
     *ate_dot = true;
   }
 
-  if (fancy_syntax(reader)) {
+  if (fancy_syntax(reader) && !(reader->flags & SERD_READ_EXACT_BLANKS)) {
     if (is_digit(buf[reader->bprefix_len + 1])) {
       if ((buf[reader->bprefix_len]) == 'b') {
         buf[reader->bprefix_len] = 'B'; // Prevent clash